Residents in two shires in WA's South West are voicing concern they were not told about a decision to relocate a Perth explosives storage facility to a nearby state forest.

The State Government-owned but privately run facility in Baldivis will be shifted to state forest number 16, 40 kilometres north of Bunbury.

This week was the first time residents were made aware of the proposal, floated some time before October 2013.

Harvey resident Noel Dew said he was concerned about the potential impacts.

"I'm surprised that the community hasn't been advised before this," he said.

Preston Beach Progress Association president John Watson said many people had holiday houses near the site and may not have realised they will be impacted.

"A lot of people have holiday homes in the area and aren't there most of time," he said.

"I wonder if they know?"

The Shire of Harvey supported a request from the Department of Mines and Petroleum, which oversees the explosives facility, to excise 130 hectares of state forest number 16 this week.

The excision also includes provisions for a sand mine to be built on the same site.

Rezoning of land expected shortly: shire

Harvey Shire chief executive Michael Parker said he expected the approval to rezone the state forest to special use to be granted shortly.

The shire's manager of planning, Simon Hall, said "it was a state Cabinet decision, not us" to keep the proposal confidential "since October 2013 while state Cabinet was making a decision on where to relocate the facility".

The forest is also partly located in the Shire of Waroona, which was also involved in the proposal, but again, found itself unable to advise residents.

Waroona Shire president Christine Germaine said most residents found out via the media this week.

"I think most found out when the newspaper hit their doorstep to be honest," she said.

Both shires have requested the mines department, DMP, to hold a full consultation with affected community in due course.

Mr Parker said the DMP had committed to this but had not provided any details as to when this would take place.

The department admits only "a few" residents were consulted during the initial planning process, including a farmer who sold part of his property to secure the buffer zone.

The forest is currently a pine plantation but the relocated facility will store detonators for the mining industry and explosives such as ammonium nitrate.

Negative impacts on neighbours a concern

The DMP acknowledged both councils had raised concerns about the proposed sand mine, including issues about increased traffic from the mining trucks and the sand extraction process.

They are not alone.

"My main concern is the conditions of the roads, with haul trucks and chemicals, and of course the extraction of sand," said Mr Dew.

WA Forest Alliance spokeswoman Jess Beckerling said she was concerned about the clearing of state forest and the negative aspects of the explosives storage facility.

"Further reductions in the area of pine plantations can have negative socio-economic effects," she said.

"There are community impacts as well that don't appear to have been adequately addressed - the transport of explosives, the release of gases and chemicals into the immediate environment and the atmosphere, and allowing for meaningful community input into this sort of planning."

DMP spokesman Phil Hine said the regulation of explosives facilities has improved since a 2006 incident in South Australia that killed three workers.

He said the new site would have strict controls in terms who could gain access to the explosives and the inventory of the site to "make sure things don't go missing".

There will also be security fencing, electronic access controls and CCTV.

Mr Hine said explosives are not "trigger-happy" like they were in the past, and there would be a buffer zone between the explosives facility, the neighbouring forest and landowners so if there was an explosion, they should not be affected.

He said a detailed fire management plan would also be developed with emergency services and the grass around the site will be kept low to prevent a grass fire reaching the surrounding forest.

The current industrial site in Baldivis is proposed to be used for housing developments.